tile: fix DWARF bug in clone() for created thread

Previously, we would see a bad frame in the gdb backtrace output, e.g.:

  (gdb) bt
  #0  foo () at foo.c:5
  #1  0x000000aaaab68ee8 in start_thread () from /lib/libpthread.so.0
  #2  0x000000aaaad01c88 in clone () from /lib/libc.so.6
  #3  0x0000000000000000 in ?? ()

With this change the bogus frame #3 is gone and we have the
same output as x86 does for the same program.

diff --git a/ports/ChangeLog.tile b/ports/ChangeLog.tile
index 67dc50c..da39a6e 100644 (file)
--- a/ports/ChangeLog.tile
+++ b/ports/ChangeLog.tile
@@ -1,3 +1,7 @@
+2012-12-14  Chris Metcalf  <cmetcalf@tilera.com>
+
+       * sysdeps/unix/sysv/linux/tile/nptl/clone.S: Fix DWARF info.
+
 2012-11-29  Chris Metcalf  <cmetcalf@tilera.com>
 
        * sysdeps/tile/s_fmaf.c: Remove redundant #defines now provided

diff --git a/ports/sysdeps/unix/sysv/linux/tile/nptl/clone.S b/ports/sysdeps/unix/sysv/linux/tile/nptl/clone.S
index de4fa13..27592cc 100644 (file)
--- a/ports/sysdeps/unix/sysv/linux/tile/nptl/clone.S
+++ b/ports/sysdeps/unix/sysv/linux/tile/nptl/clone.S
@@ -160,6 +160,8 @@ ENTRY (__clone)
    r32: the user function pointer  */
 
 .Lthread_start:
+       cfi_def_cfa_offset (FRAME_SIZE)
+       cfi_undefined (lr)
        /* Check and see if we need to reset the PID, which we do if
           CLONE_THREAD isn't set, i.e. we're not staying in the thread group.
           If CLONE_VM is set, we're doing some kind of thread-like clone,
@@ -167,7 +169,6 @@ ENTRY (__clone)
           in getpid().  Otherwise (if CLONE_VM isn't set), it's a
           fork-like clone, and we go ahead and write the cached values
           from the true system pid (retrieved via __NR_getpid syscall).  */
-       cfi_def_cfa_offset (FRAME_SIZE)
 #ifdef __tilegx__
        {
         moveli r0, hw1_last(CLONE_VM)